Preparation of roadways, building sites, embankments, and other surfaces often requires compaction to produce desired material properties. Compactors are employed to compact various paving materials such as, for example, soil, gravel, and an asphalt material. The desired degree of material compaction can vary based on the type of material being compacted and/or conditions of the material such as, for example, soil moisture content and asphalt temperature. Compaction levels are important for maintaining stability of the paving material. When undercompacted, paving surfaces lack sufficient strength to support traffic loads and are not durable. When overcompacted, asphalt and other paving materials can be permanently deformed. During a compaction process, the degree of material compaction can be measured and evaluated for conformity with job specifications.
Typical paving machines include a tractor for providing mobility and power, a hopper containing a supply of a bituminous aggregated mixture or asphalt, and a screed that lays the asphalt paving material onto an area to be paved in a strip of uniform thickness. The tractor typically includes a combustion engine configured to power operations of the paving machine, and the engine may be any of a variety of known power plants that may include gas turbine engines, natural gas powered engines, diesel engines, and gasoline engines. The asphalt paving material is heated and is applied when it has a plastic consistency so that it may be easily applied in a layer of uniform thickness. In a repaving operation, the new asphalt material may be laid upon the old surface of the roadway. It has been found that the new asphalt material adheres to the old road surface much better when the old road surface is warm. Poor results are obtained when the new asphalt material is applied upon a cold roadway. Similarly, poor results are obtained when compaction of the new asphalt material is attempted with the asphalt material being at a temperature that falls outside of a preferred range of temperatures. For this reason, specific temperature conditions exist under which paving must occur to ensure pavement quality. This limits the length of the paving season and the productivity on days when paving crews must wait for the temperature to rise. Furthermore, information regarding the temperature of the asphalt material that has just been applied by the screed is information that may be important to an operator of a compactor following the paving machine.
A screed assembly typically includes a base portion and may include one or more extension portions, each of these portions having steel screed plates mounted to the screed portions in such a manner that the plates both smooth and compress the deposited paving material, leaving behind a mat of the desired thickness. The screed plates are typically heated to prevent the asphalt material from clinging to the steel plates. In modern screed assemblies, the screed plate heaters are commonly implemented in the form of resistive electrical heaters that can be optimally positioned on or near the screed plates. Screed plates may also be heated by gas or other combustible fuel heaters. It is important to maintain a proper screed plate temperature. If the screed plates are either too hot or too cold, a poor finish will be obtained in the resulting pavement mat. In a simple screed having only base screed portions, each of the base screed portions typically includes both a heater and a temperature sensor. In such a system, each of the base screed plates may be individually temperature controlled according to feedback received from the associated temperature sensor. A wider screed requires more heaters, and the heaters are generally arranged into independent heating zones. Electric power to the heaters is controlled by a screed power module (SPM). During the paving process it is important to monitor the real-time temperature of the asphalt in order to know whether the asphalt is within an optimum temperature range for compaction.
During operation of a paving screed, an undesirable situation arises when the temperature of the new asphalt just applied by the screed cools off too much before a compactor following behind the paving screed has completed compaction of the asphalt. As a result, there is a need to identify the temperature at the surface of the asphalt in real-time as it is applied by the screed and provide the temperature information to an operator of the compactor following behind the screed. Typically, compactor vehicles used with asphalt material mats include a vehicle body and a pair of drum members or “drums” rotatably mounted to the body. Such compactor vehicles generally function by rolling over sections of the formed material mat such that the drums compact the formed material mat with every pass made over a particular section of the formed material mat, the drums also functioning to mobilize the compactor vehicles. A vibratory mechanism may be mounted within each drum to increase the extent of formed material mat compaction made by each pass of the drums. These vibratory mechanisms are generally variable in frequency and amplitude, variations in frequency enabling the compactor to be effectively operated at different speeds and variations in amplitude affecting the degree of compaction made by the drums. In a typical project for forming an asphalt mat, such as in roadway constructions, the paver vehicle forms a continuous mat of material behind the paver vehicle as the paver vehicle travels forwardly upon the base surface. One or more compactor vehicles follow the paver vehicle and generally roll over all sections of the formed material mat until the formed material mat is compacted to a desired degree or extent. Preferably, the formed material mat is formed such that the material is within a desired temperature band. If sections of the formed material mat are at a lower than preferred temperature, the compactor(s) may have to make additional passes across these sections to ensure sufficient compaction. On the other hand, if sections of the formed material mat are at a higher than preferred temperature, compactor operators will have to take caution to avoid over compacting these sections.
If would therefore be desirable to provide a system to monitor the temperature of the formed material mat as the formed material mat is being formed such that the temperature information may be used by an operator of a paver vehicle or a compactor vehicle to make appropriate adjustments to the operational parameters of the paver vehicle or compaction vehicle. Further, it would be desirable to provide a system for readily identifying sections of a formed material mat that may require additional compaction or sections of a formed material mat where it may be necessary to compact with greater caution. Furthermore, it would be desirable to provide a system for using formed sensed material mat temperature information to automatically adjust paver vehicle or compactor vehicle operations to provide an acceptable formed material mat.
One example of a system for improving operation and efficiency of paving equipment is disclosed in U.S. Pat. No. 6,749,364 to Baker et al. (“Baker”). Specifically, Baker discloses a pavement temperature monitoring system used on a paver vehicle, which sends signals to a display device on the paver vehicle to generate a graphical image of a formed material mat temperature profile. Baker's approach for improving operation of paving equipment may be overly complex, and may not provide optimum flexibility for notifying compactor operators as quickly as possible of information they need to immediately adjust operational parameters of the compactor.
The present disclosure is directed to overcoming one or more of the problems set forth above and/or other problems with existing technology.